With drones slaved to a RCC you basically have 3 options.
1. Issue a command to one, all or some of your slaved drones with the same Simple Action. You may issue two separate commands to two separate groups of drones as two separate Simple Actions. You don't need the Swarm cyberprogram to do this, just the RCC. You also don't need to be jumped into a drone to do this.
SR5 p. 267
Your RCC manages several parallel connections at once, so you can give a command to one, all, or some of your slaved drones with the same Simple Action.
2. Run the Swarm cyberprogram on your RCC to let you group two or more drones into one or more "swarm(s)". In combat, game mechanically, only the weapon of one of the drones in the swarm will attack but it will use the highest pilot rating in the swarm (or the device rating of the RCC if it is higher) and the other drones in the swarm will increase the limit and the dice pool of the attack by 1 (per drone). You don't have to be jumped into a drone to do this.
R5.0 p. 31 Swarms
...A drone (or vehicle) swarm is a network of linked drones all slaved (p. 233, SR5) to a single RCC running the Swarm program. You can include as many drones in a swarm as your RCC can slave (Device Rating x 3), or split them up among several swarms...
Each swarm ... Pilot rating is equal to the highest Pilot rating of its member drones, or the Device Rating of the RCC... When performing actions, the swarm gets a dice pool and limit bonus equal to one less than the number of drones in the swarm.
In combat, all drones attack with whatever weapons they have, but for game purposes only use a single weapon’s stats (the others are covered by the action bonuses the swarm receives)...
3. While jumped into a drone and within 10 meters of the target you can act as an assistant to all your drones by taking the Swarm Drone Vehicle Action. If successful then all your drones will gain +1 limit and a positive dice pool modifier equal to your net hits to all their attacks during the rest of the combat turn. You don't need to run the swarm cyberprogram to take this action.
R5.0 p. 179 Swarm
(CLOSE OR SHORT RANGE, ANY SPEED)
When rigged into one drone, the driver makes a Vehicle Skill + Reaction [Handling] (Terrain + number of drones) Test. If successful, net hits are added to the dice pool for any drone involved in the test for any subsequent attacks during the same Combat Turn per the rules for Teamwork Tests. If unsuccessful, ... each [drone] receives a penalty to its actions equal to the difference between the threshold and number of hits. This action must be performed with two or more drones.